Electric control for sterilizers



Jan'. 3l, 1928. 1,657,660

F. CEDERGREN ELECTRIC CONTROL FOR STERILIZERS Filed April 1, 1927 ai wg/ I6 l fnyez j! [Fred Ceder ren Patented `ian. 3l, 1928.

UNITEDl STATES PATENT OFFICE.

FRED CEDERGREN, OF HAMMOND, INDIANA, ASSIGNOR T0 FRANK S. BETZ COMPANY, 0F HAMMOND, INDIANA, A. CORPORATION OF INDIANA.

ELECTRIC CONTROL FOR STERILIZERS.

Application tiled April 1,

l This invention relates to electric controls :tor steriliziiig tanks, and the like. v

The main objects of this invention are to provide an improved form of electric control having a duel switch arrangement wherein the user manually closes the circuit to the heating element and when theliquid in the sterilizing tank gets low, i. e., just 'before the tank goes dry, the current will be automatically cut oft' from the heatingV element.

An illustrative embodiment of this invention is shown in the accompanying drawings,l

on at the time the instruments or other ar-' ticles to be sterilized are.placed in the sterilizing tank, .and then the operator need not give any further attention to the machine unless the water on other sterilizing liquid in the tank gets low. 'llie heating element ior the sterilizing tank, after being manually connected to the electric circuit, will heatthe liquid in the sterilizing tank-to a point where it will sterilize the instruments placed in the tank and will continue to boil the water indelinately. However, when the water boils away, and just before the tank goes dry, the iloor of the tank will get considerably hotter and this increased heat will actuate a bi-metallic thermostat strip to close a switclr of a shunt circuit in which is included a heated element for a second bimetallic element. This second thermostat element in turn operates a quick throw switch to its olf position and thus shuts 0E the current to the tank heating elements.

In the construction shown in the drawing, a sterilizer tank 1 is provided on the under side of its ioor 2 with a pair of longitudinally extending conductor bars 3 and 4. A.

1927. Serial No. 180,180.

series of heating coils 5 are bridged on the conductor hars 3 and 4 and are suitably insulated from the floor 2 of the tank* 1.

Current is supplied to the conductor bars 3 and 4 through lead wires 1() and 11. The wire 10 is directly connected to the conductor bar 4, and the wire 11 is connected to one terminal of a standard quick throw switch 12 which is mounted on the inner tace of the end 13.0f tank 1. The quick throw' sw1tch 12 is provided with the usual operating handle 14 protruding through the walll of the end of the tank so as to be readily accessible for manual control. The other terminal of the switch 12 is provided with a lead wire 16 which conducts the cur. rent toone terminal of a second quick throw switch 17 mounted on a bracket 18 secured i0 to depending lugs 19 and 20 which are rigidly secured to the floor 2 of the tank. The other terminal of the switch 17 is coniectgd by a lead wire22gto the conductor VManually operable means areprovided for throwing the switch 17 to its on position and comprise a rod 25 slidably mounted on the lugs 19 and 20 and having" one end thereof protruding through the side wall 26 0f'80 the tank. AA suitable head 27 is mounted on the outer end'o the rod 25 for grasping by the lingers ot' the operator. The rod 25 carries a shoulder in the form of a disk 28 rigidly secured to the rod by a set screw 29. B5 i The disk 28,15 mounted between the lugs 19 and 20 and positioned so as to abut against the switch arm 30 of the quick throw'switch 17 and push the same over to its on position whenthe rod 25 is shifted axially by 90 the operator. A coil compression spring 21 surrounds -a portion of the rod 2.5 and one end of the spring bears against the lug 20, and the other end thereof bears against a pin 33 mounted on the rod 25. A bushing 95 33 is provided on the inner surface of the side wall 26or supporting the rod and acts as a bearing therefor.

Automatic means are provided for shifting the quick throw switch 17 from its on 100 position to its of position and comprise a loi-metallic thermostatic element 35 rigidly mounted at one end on a lug 36 secured to the floor 2 of the sterilizer. The other end suitably insulated from, the 'bi-metallic element' 35, and a normally open spring switch arm 50 that is mounted on, but insulated rom, the conductor bar 4, as shown in Means are provided for closing the switch arm 50 against the inner end of an adjustable contact screw 51 threaded on the member' 4, and comprises a bi-metallic thermostatic strip 53 secured at one end by screws 54 t0 the bottom side of the tank iioor 2. The opposite end of the. element 53 is bent transversely to the remainder of the strip and is positioned to bear against the spring arm 50 when the element is flexed by overheating, so as to close the shunt circuit 40l through thearm 50 and screw 51.

'In the operation of the device the sterilizer is connected up to some suitable source of electric current and the switch 12 is turned to its on position by the switch arm 1 4. If'the switch 17 isnot alreadyv in its on position. the rod 25 is pushed inwardly by the knurled head 27 so as to throw the switch larm 30 to its on position and thereby complete the circuit to theheating coils 5. The fluid in the sterilizing tank comes to a. boil, thereby sterilizing the articles in the tank, and continues to boil indefinitely unless the water gets low. Just before the tank goes dry the, thermostatic element 53 fiexes 4 and closes the switch arm 50 against the screw 51, thereby completing the circuit through the shunt circuit 40. The current passing through the circuit 40 causes the heating` coil 41 to flex the bi-metallic thermostatic-eleof the drawings, thereby moving the switch arm 30 to its o' position and thus dis- -be altered or omitted without departing from the spirit of this. invention as defined by the following claims.

I" claim: Y

1. A sterilizer tank for containing a liquid,

an electric heating element Yfor heating the liquid therein, a main .circuit for saidvheating element, a switch in said circuit, manually operable means for closing said switch, a thermostatic element :for opening said switch, a shuntciicuit on said main circuit, a

normally open switch in said shunt circuit, a second thermostatic element located adjacent the Hoor of said tank for closing said shunt circuit switch when said tank becomes heated to a predetermined point, and a second heating element inl said shunt circuit for actuating said first mentioned thermostatic element.

A 2. A sterilizer tank for vcontaining a liquid, an electric heating element for heating the liquid therein, a main circuit for said heating element, Va switch in said circuit manually operable to its on and off positions a second switch in said circuit, an

axially slidable Yrod mounted adjacent said second switch, one end of said rod being positioned for manual control, a shoulder on said rod for engaging said switch to move said switch to its closed position, a thermostatic element for opening said second switch, a shunt circuit for said main circuit, a normally open switch in said shunt circuit, a second thermostatic element located adjacent the floor 'of said tank for closing said shunt circuit switch when said tank becomes heated to a predetermined point, and a second heating element in said shunt circuit disposed around said first mentioned thermostatic element for actuating it to open said main circuit switch.

' FRED CEDERGREN.

y Signed at Chicago this 29th day of March, ment 35, as shown in dotted outline in Fig. 1 1927. 

